2-(2{40 ethylhexyl)-quinizarin

ABSTRACT

A new alkylated quinizarin, 2(2-ethylhexyl) quinizarin, useful for marking water immiscible organic liquids; marked water immiscible organic liquids; and a method of marking said liquids with an additive which may be subsequently extracted from said liquid and easily identified by visual inspection. The method comprises dissolving in the liquid to be marked an additive selected from the group consisting of an alkylated quinizarin, the reaction product of diazotized ortho tolidine and pnonylphenol and of diazotized xylidine and p-nonylphenol. The additive is detected by extraction from the marked liquid by means of a water soluble polar organic solvent containing a base and from 0 to about 75 percent by weight of water to yield a distinctively colored extract which is identified by visual inspection. The identification may be further corroborated by chromatographic separation of the additive or by spectrophotometric analysis.

United States Patent [1 Turner et al.

[ 2-( 2 'ETHYLHEXYL )-QUINIZARIN [75] Inventors: Robert J. Turner, Lake Geneva,

Wis; David L. Booth; Richard D. Berry, both of Crystal Lake [I].

[73] Assignee: Morton-Norwich Products, Inc.

Chicago, Ill.

[22] Filed: May 14, 1973 [2]] Appl. No.: 359,963

Related US. Application Data [62] Division of Ser. No. l52,922, June 14, 197i, Pat No [52] U.S. Cl. 260/383 [51] Int. Cl. C07c 49/74 [58] Field of Search 260/383 [56] References Cited UNITED STATES PATENTS 3.399.952 9/1968 Hosoda 260/383 3.507.887 4/l970 Johnson 260/383 OTHER PUBLICATIQNS Shriner et al., The Systematic Identification of Organic Compounds, 4th Ed., (1962). Chemical Abstracts, Vol. 68, ll5697d, (1968).

[ 51 May 13, 1975 Primary Examiner-Lorraine A. Weinberger Assistant ExaminerPatrick .l. Hagan Attorney, Agent, or Firm-Jack Axelrood {57] ABSTRACT A new alkylated quinizarin, 2(2-ethylhexyl) quinizarin, useful for marking water immiscible organic liquids; marked water immiscible organic liquids; and a method of marking said liquids with an additive which may be subsequently extracted from said liquid and easily identified by visual inspection The method comprises dissolving in the liquid to be marked an additive selected from the group consisting of an alkylated quinizarin, the reaction product of diazotized ortho tolidine and p-nonylphenol and of diazotized xylidine and p-nonylphenol. The additive is detected by extraction from the marked liquid by means of a water soluble polar organic solvent containing a base and from 0 to about 75 percent by weight of water to yield a distinctively colored extract which is identified by visual inspection. The identification may be further corroborated by chromatographic separation of the additive or by spectrophotometric analysis.

1 Claim, 1 Drawing Figure 1 2-(2'ETHYLHEXYLl-QUINIZARIN This is a division of Ser. No. ISZHZZ. filed June l4. l97l. now US. Pat. No. 3,764,273,

BACKGROUND OF THE INVENTION l. Field of the Invention There is a need for a novel compound which is partic' ularly suitable for marking water immiscible organic liquids and which may be extracted easily from said marked liquids and identified. There is also a need for marked water immiscible organic liquids and for means to mark, tag or otherwise identify water immiscible liquids, such as for example, petroleum distillates including gasoline. motive fuels and fuel oils, or other organic solvents, and to distinguish such marked liquids from the otherwise identical but unmarked substances.

These needs arise primarily through the governmental regulatory action of foreign countries, including Canada and most European countries, by which taxes are imposed on motive and heating fuels. The tax regu lations of some countries provide that particular dyes and chemical markers must be added to taxable or nontaxable fuels, as the case may be, to provide a means for identification to prove or disprove the payment of taxes. For example, Manitoba Regulation Si 66 under the Motive Fuel Tax Act of Canada, provides the following at Paragraph 5 under the caption Marked and Coloured Motive Fuelz" Motive fuel used for any of the purposes mentioned in subsection (7) of Section 3 of the Act shall be given a specific colour and separate identity by means of a purple dye and a chemical marker, as may be determined by the minister.

It is, of course, necessary that the added chemical marker be capable of quick and relatively simple identification by nonscicntific personnel. In other instances and aside from tax matters, there are occasions when it is desirable to mark a particular production batch of fuel or solvent to prove the origin of the material. As is readily apparent, any marker so used must be added in small concentration, should not affect the physical or chemical properties of the substances to which it is added, and should be easily identified by relatively quick and simple means.

2. Description of the Prior Art Among the many additives and tracers which have been proposed for use or are in current use for marking or tagging motive fuels and other petroleum distillates are the metal-organic compounds, radioactive substances, and a variety of specific compounds which react with selected agents to provide intensely colored derivatives. However, many of the proposed additives and those in use have certain disadvantages which render them impractical for marking purposes. For example, the metal-organic compounds have relatively poor storage stability. The use of radioactive substances requires special cquipment and precautionary measures to prevent harmful physiological disturbances to personnel. With respect to the specific compounds which have been employed for marking purposes, there may be mentioned quinizarin, furfural, diphenylamine, and various naphthol derivatives,

Ouinizarin, though an excellent marker which is ex tracted from petroleum fuels by aqueous caustic solu tions, suffers from the disadvantage oflow solvent solubility, i.e., its solubility is generally of the order ofmagnitude of about 1 percent or less in the commonly used solvents. In the practice of marking petroleum distillates. it is convenient and often mandatory to prepare a marker preconcentrate" solution containing from at least about 2 to about 6571, and preferably from about ll) to about of the additive in a fuel-compatible solvent such as toluene or xylene. This pre-concentrate is then metered into the fuel to be marked and homoge neously incorporated therein virtually instantaneously by simple mixing. The relative insolubility of quinizarin in fuel-compatible solvents means that it must be transported and used in the dry state with the attendant handling problems due to dusting and low solubility, and precludes the possibility ofproviding a preconcentrate solution containing as much about 2 or 3% quinizarin. The use of such a relatively dilute quinizarin solution would require the addition of large volumes of preconcentrate. a situation which is undesirable both from a handling and economic point of view.

Furfural develops an intense red-colored complex with aniline acetate. However, the furfural test is ex tremely sensitive and the smallest contamination by any furfural naturally present in the liquid to be marked yields a distinct red color. Since a small quantity offur fural is sometimes produced in the normal production of middle petroleum distillates, a positive furfural test is not necessarily conclusive evidence of the presence of added furfural. The same is true of diphenyl amine and various naphthols which may originate in crude oil or arise from the cracking or refining process. Further, at the concentrations generally used in fuels, furfural is unstable to the extent that no positive identification will be obtained after a normal storage period of up to 6 months.

Other specific marking agents, for example, aniline azo beta naphthol, are extracted from fuels to which they are added by the extractants dimethylformamide or benzyl alcohol to yield a yellow colored extract. However, some times a yellow extract can be obtained by these extractants from unmarked petroleum products, thereby vitiating the test.

Accordingly, it would be desirable to provide a novel, solvent-soluble organic compound for use as an additive in marking water immiscible organic liquids, which compound is entirely foreign to said marked liquids and which compound may be easily extracted from said marked liquids and identified by visual inspection. It would also be desirable to provide a process for marking or tagging water immiscible organic liquids with an additive which has a high solubility in commercially available water immiscible organic solvents, which ad ditive is entirely foreign to said liquids, and which im parts little or no color of its own to the marked liquid, but is easily and conveniently extracted therefrom to yield a distinctive highly colored extract which may be further characterized or specifically identified by ordinary analytical methods.

It is therefore an object of this invention to provide a solvent soluble organic compound suitable as an additive for marking a water immiscible organic liquid.

It is another object of this invention to provide a solvent soluble additive for marking a water immiscible organic liquid, which additive does not occur naturally in said fluid or as a result of processing same, and which additive may be easily extracted from said marked liquid and identified by visual inspection.

It is a further object of this invention to provide a method for marking or otherwise tagging a water immiscible organic liquid with an additive which does not occur naturally in said liquid or as a result of processing same. but which additive upon extraction is easily identifiable.

it is still another object of the present invention to provide marked water immiscible organic liquids from which the marking additive may be easily extracted and identified by nonscientific personnel to provide evidence of the source of the organic liquid.

The fulfillment of these and other related objects of 30 this invention may be more readily appreciated by reference to the following specification, examples and appended claims.

SUMMARY OF THE INVENTIGN The present invention provides the compound 2(2- ethylhexyl) quinizarin having the formula ca -c-ca -ca -c which is particularly useful as an additive to a water im' miscible organic liquid for the purpose of marking or tagging same. it has been found that this compound, when added to such organic liquid. may be detected at a concentration as low as about 0.2 part per million. lts detection is effected by extraction thereof from marked organic liquids by an extractant comprising a water soluble polar organic solvent containing a base and from about 0 to about 75% by weight of water to yield a characteristically colored extract. The water soluble polar organic solvent is selected from the group consisting of methanol. ethanol, isopropanol. butanol, dimethylformamidc, dimethyl sulfoxide, acetone. ethylene glycol monoethyl ether (available under the trademark Cellosolve) and diethylene glycol monocthyl ether (available under the trademark (:arbitol), and the base is selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and quaternary ammonium hydroxides.

The proportions of water soluble polar organic solvent. water and base are as set forth in Table i.

TABLE I Water Base Solvent At least about 0.5 of an alkali metal hydroxide or an alkaline earth metal hydroxide At least about 0.5% of an alkali metal hydroxide or an alkaline earth metal hydroxide At least about 2% of a quaternary ammonium hydroxide At least about 2'7: of a quaternary ammonium hydroxide At least about 0.5% of an alkali metal hydroxide or an alkaline earth metal hydroxide At least about 2% of a quaternary ammonium hydroxide At least about (1,571 of an alkali metal hydroxide or an alkaline earth metal hydroxide At least about 2% of a quaternary ammonium hydroxide At least about 05% of an alkali metal hydroxide or an alkaline earth metal hydroxide At least about 2'72 of a quaternary ammonium hydroxide At least about (L591 of an alkali metal hydroxide or an alkaline earth metal hydroxide At least about 271 of a quaternary ammonium hydroxide Methanol Ethanol Methanol Ethanol Dimcthylformamidc Dimcthylformamidc Dimcthyl sulfoxide Dimcthyl sulfoxide lsopropanol lsopropanol Diethylcne glycol monocthyl ether From 0 to about 40% ltl 5071 3,883,568 6 TABLE 1- Continued Base Solvent Water At least about 0.5 of an Ethylene glycol alkali metal hydroxide or monoethyl cther IO 5071 an alkaline earth metal hydroxide At least about 2% of a Ethylene glycol l(| 50% quaternary ammonium monocthyl ether hydroxide At least about (1.59? of an Acetone 1U 50% alkali metal hydroxide or an alkaline earth metal hydroxide At least about 2% of a Acetone (l 50?! quaternary ammonium hydroxide At least about 29! of a Butamol ll) S0)? quaternary ammonium hydroxide The alkali metal hydroxide bases comprise lithium about 65% by weight whereas the solubilities of its adhydroxide, sodium hydroxide, potassium hydroxide, rujacent homologues are as follows: bidium hydroxide and cesium hydroxide. The preferred bases are the sodium and potassium hydroxides, with Sulubilily wcight the most preferred being sodium hydroxide. The alka- 2-n pentyl quinizarin 2l.() line earth metal hydroxides comprise the hydroxides of 2-mcthylpentyl quinizarin 26.0 magnesium, calcium. strontium and barium. The relag l i l -n-heptyl quimzarln l2.0 tive water insolubility of these hydroxides when com- 2mm) quinizan'n 3:; pared with the alkali metal hydroxides require that the W quinilafin alkaline earth metal hydroxides be employed as aqueous slurries. The quaternary ammonium hydroxides are These solubility relationships are depicted graphiwell known as strong bases and are likewise operable cally in the drawing where the number of carbon atoms in the practice of the present invention. in the alkyl group is plotted along the abscissa, and the Among the operable water soluble polar organic solpercent solubility in xylene at 25C. is plotted along the vents useful as components of the extractants of this inordinate. As is readily evident, the unusually high solu vention, those preferred are methanol and ethanol in bility in xylene of 2(2-ethylhexyl) quinizarin makes it combination with from about 10 to about 70 by a preferred marker since it can be supplied in a conveweight of water and at least about 0.5% of a base such nient liquid pre-concentrate form containing as much as sodium hydroxide or potassium hydroxide. as -65% by weight of the compound, and can be in- The foregoing extractants form a purple colored sep- 40 corporated virtually instantly in an organic liquid by arate phase (usually the lower phase) which is in dissimple admixture therewith. tinct contrast to the virtually colorless organic liquid The compound 2(2-ethylhexyl) quinizarin is come from which the extract is obtained. It was surprising niently prepared by the condensation of leuco quinizaand unexpected to find that 2(2-ethylhexyl) quinizarin rin with Z-ethylhexaldehyde according to the well is not extracted by a strongly alkaline aqueous solution, 45 known Marschalk reaction as depicted in the following as is quinizarin, but that a water soluble polar solvent equation:

(2-ethylhexaldehyde) I H l H is required to effect the extraction. Another unusual The reaction is carried out in a polar organic solvent in and unexpected property of 2(2-ethylhexyl) quinizarin the presence of a basic catalyst at a temperature rangis its extraordinarily high solubility in various Organic ing from about C. to about l2UC.

solvents, particularly in xylene, when compared to the The present invention also provides a method of solubility of its adjacent homologues. Thus the solubilmarking a water immiscible organic liquid with an addiity in xylene of 2(2-ethylhexyl) quinizarin at 25C. is tive and subsequently determining the presence of said OH CH3 CH C 1! 9 additive in said marked organic liquid said method comprising dissolving in said liquid at least about 0.2 part per million of an additive selected from the group consisting of:

[r a quinizarin derivative of the general structure:

where R is an alkyl group containing from 1 to 20 carbon atoms or the furfuryl radical.

(n) ca and extracting said additive from said marked liquid with an extractant which is the same as that hereinbefore described and set forth for use with 2(2- ethylhexyl) quinizarin to yield a characteristically col ored extract. This extract may be further characterized or identified by commonly used chromatographic or spectrophotometric analytical methods.

The term alkyl as used herein is understood to include n-alkyl, branched alkyl, substituted alkyl and cyclic alkyl. The compound is the reaction product of diazotized ortho tolidine with p-nonylphenol, and is conveniently referred to as pnonylphenol ortho tolidine p-nonylphenol. Similarly, the compound 19 N=N/ is the reaction C product of diazotized xylidine and pmonylphenol, and is conveniently referred to as xylidine pnonylphenol, For the sake of convenience, this shorthand nomenclature will be employed for the reaction where R is an alkyl group containing from 1 to 20 carbon atoms. or the furfuryl radical,

said method comprising admixing said marked liquid with an extractant comprising a water soluble polar organic solvent containing a base and from about U to about 75% by weight of water. and agitating the admixture to obtain an extract having a characteristic and distinct coloration. The extractant employed is the same as that described and set forth for use with 2(2- ethylhexyl) quinizarin.

The method of the present invention has broad appli- The marking ingredient of the marked water immiscible liquid is capable of being extracted from said liquid with the same extract-ant as that herein before described and set forth for use with 2(2-ethylhexyl) quinizarin to yield a characteristically colored extract which may be further characterized or identified by commonly used analytical methods.

This invention also provides a method of determining 1 the fact of marking or tagging or an apparently substanwhere R is an alkyl group containing from 1 to 20 car bon atoms, or the furfuryl radical.

CH CH and (III) cability for marking a wide variety of water immiscible organic liquids, such as for example, aromatic solvents, aliphatic solvents, mixed aromatic-aliphatic solvents, chlorinated solvents, motive fuels such as gasoline, jet fuel, diesel fuel and fuel oils, lubricating oils, vegetable oils and esters. The present method is particularly useful in marking petroleum products such as gasoline, and other motive and heating fuels, and will therefore be elucidated in connection with marking these products, it being understood, however, that the invention is not limited to this particular field of application.

It is generally agreed by those skilled in the art of marking fuel or other immiscible organic liquids that the essential requirements of a successful additive marker are:

l. The additive or marker must be a substance which is otherwise foreign to the liquid to be marked.

2. lt must be detectable in low concentrations by a simple qualitative test which can be carried out by nonscientific personnel at any location.

3. lt must have a high solubility in aliphatic and aromatic solvents so that liquid preconcentrates" of rela- 50 tively high additive concentration may be prepared.

4. lt must have good storage stability and be physiologically innocuous.

5. lts presence must be capable of absolute corrobo rative identification by confirmatory laboratory tests.

The additive markers of the present invention fulfill these requirements and overcome the disadvantages noted for prior art additives. It should be understood that the primary function of the present markers is not as dyes and that there is a distinction between a dye and a marker used to identify or tag another substance. A dye imparts a particular and obvious visible coloration to a fuel, for example, but is not necessarily extractable therefrom. A marker need not itself impart a visible coloration to a fuel or solvent to which it is added, but its presence must be detectable and identifiable, either by extraction or other means. The markers of this invention, at the concentrations usually employed in tagging petroleum distillates. provide little visible coloration to the host liquid but exhibit characteristic colored concentrates when isolated by the extractants of the present invention.

The markers of the present invention are conveniently provided in suitable pre-concentrate" solutions in toluene, xylene or other commercially available solvents. As previously stated, the concentration or marker in such pre-concentrates ranges from about 2 to about 65% and preferably from about It] to about 60%. The effective concentration of marker in the marked fluid may be as low as about 0.2 part per million and still provide a distinctively colored extract. Concentrations of additive ranging from about 1 to about 30 parts per million are preferred. Although concentrations in excess of 30 ppm. are operable, it is generally not necessary to exceed this level since the desired effect may be obtained at lower concentrations with commensurate savings in cost.

As hereinbefore mentioned, quinizarin is completely extracted from organic fluids by strongly alkaline aqueous solutions. It was therefore surprising to find that, in contrast to quinizarin, 2(2-ethylhexyl] quinizarin and the other alkylated quinizarins of the present invention are not extracted from petroleum distillates by aqueous alkaline solutions. It was discovered however, that they are readily extracted by strongly alkaline aqueous solutions provided there is present a significant proportion of a water soluble polar organic solvent. As stated, this solvent may be methanol, ethanol, isopropanol, butanol, dimethylforrnamide, dimethyl sulfoxide, acetone, Cellosolve and Carbitol. in the instance where the preferred solvents methanol and ethanol are used, the concentration of these solvents may vary from 100 to about 60%, i.e., the water content may range from to about 40: The preferred bases, sodium hydroxide and potassium hydroxide, may be present in a concentration as little as about 0.5%, although it is preferred to use from about 3 to 5%, Concentrations greater than 5% are operable but unnecessary since the lower concentrations provide adequate extraction. In one pre ferred aspect of this invention, the extract-ant comprises about 75 90% methanol, about IO'Z H 0 and about 5% of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide in practice. a pre-concentrate marker solution is conveniently provided by dissolving in toluene or xylene from about Ill 65% of one of the present markers. This so-called pro-concentrate may be incorporated virtually instantaneously and homogeneously in gasoline or other fuel in such proportion to provide at least about 0.2 ppm, and preferably from about l to about ppm of marker additive in the host liquid. The

marker provides only a slight tint to the gasoline and its presence is otherwise not apparent. Asa matter offact. 5 if desired. it is possible to add in addition to the marker conventional dyes which actually color the gasoline, since these coloring agents will not interfere with the present marking method. Thus it is possible to provide a product containing a combination of any desired dye and marker. For identification purposes, the extraction of marker from the gasoline may be conveniently carried out at the site of the gasoline storage tanks or on the highway by the following procedure. A 125 ml. stoppered separatory funnel is filled with ltltl ml, of the marked fuel. Five milliliters of the extractant is added and the whole is shaken vigorously for about 30 to 40 seconds. In the instance where the additive is one ofthe present alkylated quinizarin derivatives, a bright purple colored layer immediately settles out in the lower phase and is readily visible. Where the additive is one of the reaction products of diazotized ortho tolidine with pnonylphenol or xylidine with p-nonylphenol, the color of the aqueous extract is bright red. The extraction test is simple and can be carried out quickly and conveniently by non-scientific personnel. A control with unmarked fuel demonstrates that no color is removed by the procedure. This quick on-the-spot test can be corroborated by the following more formal laboratory identification procedure which may be employed when the marker is 2(2-ethylhexyl) quinizarinv The marked fuel is percolated through a column of silica gel. A convenient column size is Va X 2 inches. It is best to prc-wet the column with isooctane and to flush the remaining fuel with isooctane after passage. lsooctane is also recommended for dilution of viscous oil samples to speed percolation.

After the passage of the fuel through the column a 1-2 cm. orange zone will be present. This contains virtually all of the standard dyes used in petroleum prod acts and almost all impurities and additives. The marker is also contained in or near this zone. The marker can be separated from the impurities and be observed to move down the column by elution with benzene. With a properly packed column. the marker can be collected in 10 ml. of effluent as an orange color. Colorimetric examination ofthc effluent against a standard yields semi-quantitative information on the marked fuel content. 2(2-ethylhexyl) quinizarin has a major absorption maximum at 489 mu.

Confirmation of the marker can be made by at least two additional procedures.

l. Spectrophotometric examination of the caustic extracts will show a characteristic absorption maximum for this marker at 598 mu. and a second peak at 560 2. Thin layer chromatography on silica gel substrates with benzene eluent will show a characteristic R; value for the marker.

in the instance where the marked organic liquid is a diesel fuel or other oily liquid prone to present emulsification problems during extraction, the marked liquid is first diluted with an equal volume of a petroleum distillate such as, for example, one commercially available under the trademark Skellysolve B. If substances are present in the liquid to be marked which interfere with the analytical confirmation of the additive by the spectrophotometric method, these substances can be removed by first prccxtracting the marked liquid with an fill aqueous methanol solution followed by extraction with an aqueous caustic solution.

A preferred alkyl quinizarin marker of this invention is 2(2-ethyhexyl) quinizarin. This marker. as previously stated. by comparison with the other alkylated quinizarins ofthis invention displays unexpected and unusually higher solubility in a variety of solvents and particularly in xylene.

The reaction products of diazotized ortho tolidine and diazotized xylidine with p-nonylphenol also form suitable markers. These products and mixtures thereof, perform satisfactorily as markers in the same concentration as and in a manner similar to the alkyl quinizarins. In fact. the extraction procedure employed for the alkyl quinizarins also serves for these coupled products which generally yield a reddish colored extract.

For a more complete understanding of the present invention. reference is now made to the following spe cific examples illustrating the novel marking compound, marking process and marked fuels of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 Preparation of Alkyl Quinizarin Derivatives H OH H RCHO I where the following aldehydes yield the indicated alkyl quinizarins:

ALDEHYDE QUINIZARIN Acetaldehyde n-Propylaldehydc lsohutyraldehyde n-Butyraldehyde n-Valeraldehyde n-Hexaldehyde 2-Mcthy lpentylaldehyde nHeptaldeh de Z-Ethylhexaldehyde mOctylaldehyde n-Nonyialdehydc n-Dodecylaldehytle Octadccylaldehyde Furfuraldehyde Cyclohexane Carhoxaldehyde' The reaction is carried out in a polar organic solvent. e.g.. Carbitol or dimethylformamide in the presence of a basic catalyst. such as for example. benzyltrime thylammonium hydroxide or piperidinium acetate. The condensation is conducted at a temperature ranging from about C. until complete. The completion of the reaction is determined by thin layer chro matograph (TLC) on silica gel. When the condensation is complete. the reaction is cooled slowly to room temperature (or colder) and the alkylated quinizarin is allowed to crystallize. The product is filtered, washed with methanol and water, and then air dried. The prod uct may be purified by recrystallization from benzene or petroleum naphtha. Thus Z-ethyl quinizarin. Z- propyl quinizarin and Z-butyl quinizarin were recrystallized from benzene whereas 2-pcntyl quinizarin. 212- methylpentyl) quinizarin. 2(2-ethylhexyl) quinizarin. ZheptyI quinizarin and 2(n-dodccyl) quinizarin were recrystallized from petroleum naptha,

EXAMPLE 2 The following alkylated quinizarins were each added to white gasoline and to No. 2 fuel oil respectively at a concentration of 10 ppm and 1 ppm respectively:

Z-n-propyl quinizarin Z-n-butyl quinizarin 2n-pentyl quinizarin 2(2methylpentyl) quinizarin Z- n-heptyl quinizarin 2(2-ethylhexyl) quinizarin 2-octadecyl quinizarin was added to white gasoline at a concentration of 10 ppm.

A sample of l()() milliliters of each of the marked fuels was extracted with 5 ml. ofa 5% aqueous sodium hydroxide solution. There was no detectable extraction of any of the above alkylated quinizarin markers.

The above procedure was repeated with the exception that each of the marked fuels was extracted with 5 ml. of methanol containing 5% by weight of sodium hydroxide. A deep purple colored lower phase indicating extraction of the alkyl quinizarin was obtained from each sample of marked fuel.

EXAMPLES 3 through on A marked petroleum fuel (white gasoline) was pre pared by adding thereto 2(2-ethylhexyl) quinizarin at a concentration of [0 ppm. One hundred milliliter samples of the marked fuel were extracted separately in a separatory funnel with 5 ml. of each of the following extractants, with the indicated results as set forth in the following examples:

EXAMPLE EXTRACTANT COLOR OF EXTRACT BASE SOLVENT CONCENTRATION 3 5% NzlOH Methanol 100?! Purple 4 5% KOH Methanol 1009/ Purple 5 572 NuOH Methanol/Hp 90/10 Purple (1 5% NaOH Methuno1/H. ,O 80/20 Purple 7 5'3 NuOH Methanol/H O 70/30 Purple 8 552 NuOH Methanol/H O 60/40 Purple 9 5'3 NuOH Methunul/H. ,O 50/50 Colorless No Extraction 10 3 2 NuOH Methatno1/H. ,O 90/10 Purple 1 1 I? NuOH Methanol/H O 90/10 Purple 12 171 NuOH Methanol/H O 90/10 Purple 13 0.59% NuOH Methanol/H O 90/10 Purple 14 57? NuOH Ethanol/H O 90/10 Purple 15 5% BTMAH Methanol 1007: Purple 16 5% BTMAH Methanol/H O 90/10 Purple 17 1% BTMAH Methanol/H O 90/10 Purple 18 l?! BTMAH Methanol/H O 80/20 Purple 19 151 BTMAH Methanol/H O 70/30 Purple 20 l7( BTMAH Methanol/H O 50/50 Colorless No Extraction 21 5% BTMAH Methanol/H O /75 Colorless No Extraction 21 5% BTMAH Ethanol/H O 50/50 Purple 23 5% LiOH Methanol/H O 90/10 Purple 24 5% BulOH/ Methanol/H O 90/10 Purple 25 5% BalOHl Methanol/",0 70/30 Purple 16 5)? Ca(OH Methanol/H O 90/10 Purple 27 MglOH 1- Methanol/H O 70/30 Purple 28 5'? NaOH Dimethylformamidc/ 80/20 Purple H 0 29 57: NuOH Dirnethylformamide/ 50/50 Purple H 0 30 5% NaOH Dirncthylformamide/ 25/75 Purple H 0 31 19? NaOH Dimethylfurmamide/ 90/10 Purple H 0 12 1% NaOH Dimethylformamide/ 80/20 Purple H 0 33 5% BTMAH Dimethylformamide 100% Purple 34 5% BTMAH Dimethylformamide/ 50/50 Purple H 0 35 5% BTMAH Dimethylformamide/ 25/75 Purple H 0 36 2% BTMAH Dimethylformamide/ 25/75 Purple H 0 37 17( BTMAH Dimethylformamide/ 25/75 Colorless No H O Extraction 38 57: NaOH Dimethyl sulfoxide/ 50/50 Purple 39 5% BTMAH Dimethyl sulfoxide 100% Purple 40 5% BTMAH Dimethyl sulfoxide/ 90/10 Purple H-,O 41 27: BTMAH Dimethyl sulfoxide/ 25/75 Purple H 0 42 1% BTMAH Dimethyl sulfoxide/ 25/75 Colorless 4 No H O Extraction 43 1% NaOH lsopropanol/H O 90/10 Purple 44 5% NaOH lsopropanol 100% Colorless No Extraction 45 5% BTMAH lsopropanollH O /50 Purple 46 51 BTMAH lsopropanol/H,O 25/75 Colorless No Extraction 47 5% BTMAH lsopropanol 100% Colorless No Extraction 48 17: NaOH Curbitol/H O 90/10 Purple 49 1'71 NuOH CarbimI/H O 50/50 Purple 50 591 BTMAH Curbitol 100% Purple 51 5% BTMAH Curbitol/H O 90/10 Purple 52 5'71 BTMAH Curbitol/H O 50/50 Purple 53 59? BTMAH curbitol/H o 25/75 Colorless N0 Extraction 54 5% KOH Celloso1ve/H O 90/10 Purple 55 5% BTMAH Ccllosolve/H o 50/50 Purple 56 5'71 BTMAH Cellosolve/H O 25/75 Colorless No Extraction 57' 5% BTMAH Cellosolve 100% Colorless 4 No Extraction 58 156 NaOH BuIunoI/H O 90/10 Colorless No Extraction 59 1% NaOH Butunol/ILO 50/50 Colorless No Extraction no 5% BTMAH Butunol 100% Colorless No Extraction ol 5% BTMAH But'rin01/H O 90/10 Purple 62 5% BTMAH Butunol/Hl O 50/50 Purple 63 592 BTMAH Butanol/H. ,O 25/75 Colorless No Extraction 64 1'7 NuOH Acetone/H O 90/10 Purple 65 57( BTMAH Acetone 100% Purple 66 5% BTMAH Acetone/H O /10 Purple The terminology "Methanol/H O 90/100" means 90)? methanol 10; water lw/w 1. Benz! ltrinteth lummonium hydroxide EXAMPLE 6? The marker 2(Lethylhexyl] quinizarin was added to the following commercially available motive fuels at a concentration of l ppm and ppm respectively, and subsequently identified by extraction of l00 ml. of marked fuel with ml. of an extractant comprising 57: NaOH in 90/l0 methanol/water to yield a distinctive bright purple color in the extract:

Moti\e Fuel Manufacturer Premium and Regular Gasoline Premium and Regular Gasoline Premium and Regular Gasoline Premium and Regular Gasoline Premium and Regular Gasoline Premium and Regular Gasoline Premium and Regular Gasoline Premium and Regular Gasoline Standard Oil Company Gulf Oil Company Sinclair Oil Company Shell Oil Company Citgo Oil Company Mobil Oil Company Skelly Oil Company Phillips Petroleum Company Motive Fuel White Gasoline No. l Fuel Oil No. 2 Fuel Oil Aviation Gasoline Jet Fuel Kerosene Diesel Fuel EXAMPLE 68 The substituted alkyl quinizarin Z-furfuryl quinizarin.

OH l l I ca l OH was added to white gasoline at a concentration of ppm. It was subsequently extracted from [00 ml. of the marked fuel with 5 ml. of an extractant comprising 5% NaOH in 90/10 methanol/water to yield a purple colored extract in the lower aqueous phase.

EXAMPLE 69 The marker 2(2-ethylhexyl) quinizarin was added to gasoline, No. 1 fuel oil, No. 2 fuel oil and diesel fuel, respectively, at a concentration of l0 ppm. The efficiency of the extractants of the present invention in extracting all of the marker was determined by the following procedure. The absorbance at 489 mu. of the additive in the petroleum fuel was determined with un marked fuel as a blank. One hundred ml. ofthe marked petroleum fuel and 10 ml. of 5% NaOH in 90/10 methanol/water were placed in a first 125 ml. separator) funnel. The funnel was shaken for at least 60 seconds and the layers were allowed to separate. The lower layer containing the marker was drawn off into a second separatory funnel containing 10 ml. of HCl and 30 ml. of unmarked petroleum fuel. The causticmethanol/water extraction procedure was repeated several times on the contents of the first funnel and the extracts were combined with the acid-fuel mixture in the second funnel (the pH of the aqueous layer must be acidic). This results in the transference to the marker back to the petroleum fuel layer.

The aqueous HCl-petroleum fuel mixture was shaken and allowed to separate. The aqueous layer was drawn off into a third separatory funnel and extracted twice with 30 ml. portions of petroleum fuel. These extracts were combined with the petroleum fuel in the second funnel and the whole was diluted with l00 ml. with petroleum fuel. The wet fuel was filtered to remove occluded water and its absorbance at 489 mu. was determined, using unmarked petroleum fuel as a blank.

The results were as follows:

Two Extracts Four Extracts White Gasoline I00?! recovered No. l Fuel Oil 969? recovered N0. 2 Fuel Oil P 9791 recovered Diesel Fuel 97' reco\crcd EXAMPLE The solubility of each of the following markers of the present invention was determined in xylene at 25C. These results are set forth in Table I.

EXAMPLE 7] The product of the coupling reaction between diazotized ortho tolidine and p-nonyl phenol is prepared by a conventional coupling procedure after which it is isolated and purified to provide a marker which may be represented as follows: p-nonylphenol ortho tolidine p-nonylphenol. In similar manner the product of the coupling reaction between diazotized xylidine and p-nonylphenol is prepared to provide a product which may be represented as follows: xylidine pnonylphenol. Each ofthese markers was added, respectively, at a concentration of 10 ppm. to white gasoline. One hundred milliliters of the marked gasoline was extracted with 5 ml. of a solution consisting of 5% NaOH in /10 methanol/water to yield a bright red color in the extract in each instance.

EXAMPLE 72 The marker 2(2-ethylhexyl) quinizarin was added at a concentration of ppm to each of the following water immiscible liquids:

Chloroforrn Methylene chloride Perchloroethylene Benzene Toluene Xylene Skellysolve B (an aliphatic petroleum distillate) Mineral spirits lsooctane l. The compound 2(2-ethylhexyl) quinizarin.

in -i 11 

1. THE COMPOUND 2(2-ETHYLHEXYL) QUINIZARIN. 